Summary On 04 August 2006, two light aeroplanes collided in mid-air approximately 1nm west of the town of Caledon, Ontario. Both aeroplanes were operating in accordance with visual flight rules in ClassE airspace. The collision involved a Cessna172P aeroplane (serial number17275680, registration C-GFGD) operated by the Brampton Flying Club and being flown by an instructor and student, and a Cessna182T aeroplane (serial number18281612, registration C-GCHN) being flown by its owner. C-GFGD was southeastbound in a gradual descent, wings level. C-GCHN was northbound in straight and level flight. The angle between the tracks of the two aeroplanes was approximately 120. During the collision, the right wing was torn from C-GCHN and the aeroplane became uncontrollable. C-GFGD sustained damage to the nose and cockpit areas. Both aeroplanes crashed in close proximity to the point of collision. The three occupants of the aeroplanes received fatal injuries and both aeroplanes were destroyed. There was a small post-impact fire as a result of debris from one aeroplane severing an electrical power line. There was no fire in the main wreckage of either aeroplane. The accident took place at 1234 eastern daylight time at 4351'29.6"N, 0801'12.8"W. Ce rapport est galement disponible en franais. Minister of Public Works and Government Services Canada 2008 Cat. No. TU3-5/06-2E ISBN 978-1-100-10120-0 Other Factual Information The collision occurred in daylight conditions that were suitable for visual flight, and the sun was high. Neither the weather nor the sun was a factor in the accident. The Cessna 172, registration C-GFGD, was signed out for an instructional flight in preparation for the student pilot's private pilot flight test. The instructor pilot was pilot-in-command and carried overall responsibility for the conduct of the flight. The student pilot was most likely the pilot flying the aeroplane and would be expected to carry out all of the appropriate checks and functions. One of the instructor's roles is to monitor the performance and techniques used by the student in carrying out this and other cockpit functions. The Cessna182, registration C-GCHN, was on a visual flight rules (VFR) flight plan from Burlington Airpark, Ontario, to Collingwood Airport, Ontario, to the Parry Sound Area Municipal Airport, Ontario. The flight planned altitude was 3500feet. All the crew members of the aeroplane were appropriately qualified, held valid medical certificates, had normal corrected or uncorrected vision, and were familiar with local conditions. The results of the autopsies and review of medical history did not indicate incapacitation or impairment before the collision. Both aeroplanes were equipped with three-point lap/shoulder restraints. C-GCHN was also equipped with lap-belt air bags. Impact forces were outside the design limits of the restraint systems and the impact was not survivable. Radar data indicated that C-GFGD was descending progressively from 3800feet to 2400feet on a southeasterly track toward the Brampton Airport while C-GCHN was northbound toward Collingwood maintaining an altitude of 2400feet. The two aeroplanes converged at an angle of 120 with a rate of closure of approximately 200knots (340feet per second). The flight paths and collision geometry are depicted in Appendices A and B. Each aeroplane presented an aspect angle 30 to the other. Examination of the wreckage indicated that the aeroplanes struck each other as shown in AppendixC, wings level and heading unchanged, indicating that neither aeroplane took evasive action. The right wing detached from the fuselage of C-GCHN. The main wreckage of each aeroplane was found along its direction of flight. There was no indication of pre-impact damage or discrepancy affecting the operation of either aeroplane before the collision. Records for each aeroplane indicate that both were maintained in accordance with applicable regulations. There was property damage to the electrical power line and to a soy field in which one aeroplane crashed. Both aeroplanes were equipped with anti-collision strobe lights and normal practice was for them to be on during flight. Both aeroplanes were equipped with functioning transponders. C-GCHN was also equipped with a traffic information service (TIS) system that can provide a display of nearby aircraft using information provided by ground-based radar; this service is not available in Canada. Neither aeroplane was equipped with a traffic alert and collision-avoidance system (TCAS) nor was such equipment required by regulation. Both aeroplanes had single-piece front windshields, which were in good condition. Field of view and position of the other aeroplane and of the sun are presented in AppendixD. The collision occurred in ClassE airspace (see AppendixA) where there is no requirement for an air traffic control (ATC) clearance or radio contact with air traffic services. In this type of airspace, there is no requirement for position reports, traffic advisory calls, or for aircraft to be on a common very high frequency (VHF) radio frequency. Aircraft are not required to have a communication radio, a radar transponder, or collision-avoidance equipment on board. It is unlikely that there was any communication between the two aircraft. The Brampton Flying Club uses a practice area west of Orangeville, Ontario (see AppendixA), for flight training. The flying club has a standard procedure to fly a track parallel to Highway10 between the Brampton Airport and the practice area, staying to the northeast of the highway outbound to the area and over gravel pits about one mile southwest of the highway returning to the airport. Neither the practice area nor the routes to and from Brampton Airport are published; both are heavily used. Terrain elevation in the area is 1400to 1500feet above sea level (asl). There are built-up areas and noise-sensitive locations in the vicinity, and aircraft normally maintain 1000feet above ground level (agl) in the area. The floor of nearby ClassC airspace is 2500feetasl; therefore, aircraft without an ATC clearance must maintain 2400feet asl or lower. Radar data for this area during a 10-day period around the accident indicated a heavy volume of VFR traffic below the ClassC floor and several occasions of traffic within about 1500feet horizontally and 200feet vertically of each other. Canadian Aviation Regulations concerning collision avoidance and right-of-way are premised on the principle of see-and-avoid. A pilot's ability to visually detect another aircraft is affected by many factors, including physiological limitations of the human visual and motor-response systems (see AppendixD), obstructions to field of view, aircraft conspicuity, pilot scanning techniques, workload, and alerting to the presence of another aircraft. There is considerable guidance and research material on this subject (see AppendixF for endnotes), salient aspects of which are as follows: Specific paint schemes and patterns may have an advantage in certain conditions but none has an overall advantage over another.i, ii, iii Anti-collision/strobe lights do not have a significant effect in bright daylight.iv Landing lights are useful when the opposing aeroplane is in the direct beam.v The United States Federal Aviation Administration (FAA) recommends that pilots spend 75percent of the time scanning a 180by 30field of view outside the cockpit. Estimates vary from 54seconds to 9minutes to perform the scan. A total of 12.5seconds is required after first detection for pilot recognition and reaction to avert a collision. In practice, pilots spend 33percent of the time scanning outside mainly within 10of the direction of flight.vi Proportion of time spent scanning outside the cockpit tends to increase. Attention is focussed on known location of conflict. Probability and range of detection increase. Maximum discernable range for 6/6visual acuity: 8.5km. Earliest likely detection range and time: 3.2km, 28seconds.vii Probability of detection for 33percent outside scan time: 25percent. Maximum discernable range for 6/6visual acuity: 8.5km. Earliest likely detection range and time: 3.2km, 28seconds.vii Probability of detection for 33percent outside scan time: 25percent. TSB records indicate that 16mid-air collisions occurred in Canada during the preceding 10-year period resulting in 27fatalities and 5serious injuries. Of these accidents, 4involved some form of formation flight or gliders operating in thermals, and the remainder involved aircraft that were not associated with each other. None were within ClassD or higher airspace, and none occurred under ATCor advisory service. A total of 6accidents occurred within the traffic zone of an uncontrolled airport and 6involved flight beneath controlled airspace associated with a major airport. One of these occurrences led to a Transport Canada safety review in 2001-2002 of VFRoperations in the vicinity of Toronto, Ontario,1 significant aspects of which are as follows: Routing restrictions and confined vertical dimensions contribute to traffic congestion. Two system deficiencies were identified concerning availability and quality of aeronautical information and lack of standard operating procedures for VFRoperations. A number of risk scenarios were identified in which a mid-air collision was a potential outcome that was considered unlikely within the five-year time horizon of the study. Several recommendations were made to address the deficiencies and risks. There has been little progress in implementing the recommendations. Another of the occurrences took place approximately 5miles west of the location of this accident and in similar weather conditions. It involved a Cessna172 aeroplane on an instructional flight and an ultralight aeroplane on a pleasure flight. The right main wheel of the Cessna172 rolled along the top surface of the left wing of the ultralight. The ultralight was damaged but was able to land safely. The Cessna172 was undamaged. Neither aeroplane saw the other before the collision. There is also a history of occurrences in which there was a risk of collision between commercial air traffic on approach to Hamilton, Ontario, and glider activity in ClassE airspace. Gliders have an exemption from the requirement to carry transponders, making them invisible to ATCand the TCAS. Transport Canada found that these occurrences also indicate problems with respect to airspace structure, classification, and ATC operating procedures in airspace adjacent to Toronto ClassC airspace.2 According to international agreement,3 regardless of the type of flight plan, pilots are responsible for averting collisions when in visual flight conditions, in accordance with the principle of see-and-avoid. Flights operating under instrument flight rules (IFR) are separated by ATC from other known air traffic. VFR aircraft may also receive traffic advisories from ATC. Most large commercial aircraft are required to be equipped with a TCAS, which provides an automated traffic alert and resolution advisory based on automated exchange of transponder information between the two aircraft. There are some proximity alerting devices available for light aircraft that depend on receiving transponder signals from the other aircraft. The above-mentioned systems at present depend on aircraft being equipped with a transponder. Without a transponder, aircraft are invisible to ATC and TCAS devices. Cost, weight, and power consumption have hindered the fitting of transponders in many light aircraft and gliders. The NAV CANADA concept4 for future air traffic management (ATM), consistent with international plans in the International Civil Aviation Organization (ICAO), includes introducing automatic dependent surveillance broadcast (ADS-B) and ultimately replacing surveillance radar systems when they reach the end of their useful life, which is foreseen to be 10plus years in the future. Aircraft equipped with ADS-B transmit a position derived from the Global Navigation Satellite System (GNSS) to receivers on the ground and on suitably equipped aircraft. The result is radar-like and TCAS-like capability. The ADS-B is expected to facilitate low-cost technology to provide enhanced collision-avoidance capability for light aircraft. A number of international studies (see AppendixF) have addressed the overall issue of risk of collision and effectiveness of the see-and-avoid principle. All acknowledged the underlying physiological limitations at play and that, when mid-air collisions occur, "failure to see-and-avoid is due almost entirely to the failure to see."5 One study stated that "our data suggest that the relatively low (though unacceptable) rate of mid-air collisions in general aviation aircraft not equipped with TCAS is as much a function of the 'big sky' as it is of effective visual scanning."viii Specific results relevant to this occurrence are as follows: A French studyix of mid-air collisions in a 10-year period found that the see-and-avoid principle was becoming no longer adequate as the sole means of averting collisions. An Australian studyx concluded that the see-and-avoid principle, in the absence of traffic alerts, has serious limitations and that the historically small number of mid-air collisions is as much due to low traffic density and chance as it is to the successful operation of see-and-avoid. The most effective response to the many flaws of see-and-avoid is to minimize the reliance on it. A German studyxi on the detection of gliders and small motorized aircraft found that passive conspicuity measures did not overcome the underlying limitations of the see-and-avoid principle. It recommended further development and promotion of GNSS and ModeS transponder technology, noting that there is already on the market a GNSS-based system that is ADS-B compatible, called FLARM.6 That system is in use on gliders and provides collision-avoidance information. Eurocontrolxii examined risk of collision scenarios between uncontrolled VFR general aviation aircraft and both other uncontrolled VFR traffic and IFR commercial air traffic and found that see-and-avoid was ineffective as the sole means of averting collisions. It preferred technological solutions, specifically increased use of ModeS transponders to function with secondary surveillance radars (SSRs), aircraft collision-avoidance systems (ACAS)/TCAS, TIS, and ADS-B, and to that end endorsed continued development of the Light Aviation SSR Transponder (LAST) including low-powered variants. It found that systems such as FLARM could reduce the risk of collision between VFR aircraft. A British Royal Air Force studyxiii into mid-air collisions deemed to be random found that the probability of conflict is proportional to the square of the traffic density and recommended avoiding altitude restrictions that concentrate traffic.